Automatic telephone system



March 24. 1925.

1,531,220 w. T. POWELL 7 AUTOMATIC TELEPHONE svsmm Filed Sept. 18 1 22 2Sheets-Sheet 1 PRIMARY LINE SWITCH.

INVENTOR Q \MNFRED T owa March 24. 1925. I E 1,531,220

.w. T. POWELL wwomnc TELEPHONE SYSTEM- Fild Sept. 18. 1922 2Sheets-Sheet. 2

om: azcouumnv urns swrrcH.

I v I EVEN SECONDARY um; syHTCH.

LINE FIN-DER.

INVENTOR ATT RNEY wmrmso T. POWELL.

Patented Mar. 24, 1925.

j UNITED STATES PATENT OFFICE.

wmrnnn T. rownmaron EocHEsTEE, NEW .YoEx, essrenon. To THE sTEoMnEEGcAELso'N TELEPHONE MANUFACTfiRING A OORPORATION OF NEW YORK.

COMPANY, or EoorrEsTEE. NEW YORK,

AU 'IOMATIG TELEPHONE SYSTEM.

As iration filed September To all whom it may concern; a

Be it known that- 1, WIrITrRED T. PownLL, a citizen of the UnitedStates, residing at Rochester, 'in the county of Monroe and State of NewYork, have invented certain new and useful'lfnpfrovements in AutomaticTelephone Systems, of which the following is a full, clear, concise, andexact description. a v

ThlS invention relates to telephone sys line switch for each line wouldseem to be i an unnecessary expense.

v For this reason it has been proposed to employ finder switches,

that is, a non-numerical switch for each trunk circuit which switchoperates on the initiation of a call to connect the calling line to anidle trunk. This arrangement, while.

it has the advantage of being much less expensive than the formerarrangement is not entirely satisfactory. due to the fact that thecalling line isnot alway extended to the idle trunk before the callingsubscriber starts to dial the wanted number with the result that the.call is either lostor mutilated.

In accordance with the present invention it is proposed to retain theadvantages of both systems and eliminate the disadvant ages of the sameby employing line switches which are common to several telephone lineswith line" finder switches which are commo to several trunk circuits. c

Other features of this invention will ap pear from the detaileddescription and appended claims.

In the drawings" Fig. 1 represents four subscribers substations'and thelines extendingjtherefrom to a-line-switch shown at 1t, 1522. Serial at.588,786.

the lower right hand corner of this figure. It will be noted that thesubstation circuits of only one telephone line are shown in detail butit will be understood that thesubstation circuits of the other threesubstatio'ns will beidentical with that shown in the upper left handcorner ofthis figure. In the upper left hand corner of Fig. 2 there isshown the operating circuits of a line finder switch, and in the upperright hand corner of this figure there is shown an odd secondary lineswitch while in the lower right hand corner there is represented an evensecondary line switch. At the extreme right of Fig. 2 there is indicatedan impulse relay and a slow releasing relay which relays are located ata numerical switch such as a selector or connector employed in atelephone connection.

For convenience in describing this invention,'the lines of the telephonesystem are divided into groups of one hundred lines each, which groupsare further sub-divided intosub-groups of four lines, each subgrouphaving a primary line switch for its individual use. It will thus beseen that twenty-five primary switches are provided for each group ofone-hundred lines.

By referring to the drawing of Fig. 1 it will be noted that theprimaryline switch is provided with five sets of brushes, which arerotatable in the well-known manner to engage any one of ten sets offixed terminals of the switch. Ten pairs of primary trunks are multiplyconnected to corresponding fixed'terminals inthe primary line switchesof the group, each of these t-Wenty trunks terminates in a. secondaryline switch whose brushes have access to ten sets of terminals in whichten secondary trunks terminate. Through the actionof various relays,when two of the four'lines of a subgroup are in use the remainingtwolines are connected to the terminals of ten finder switches, theseswitches are, of the same type as the line switches except that they areprovided with twenty-five sets of fixed terminals instead of ten sets ofterminals as in the ,case oft-he previously mentioned switches. Thebrushes of each finder switch are connected to one pair of primarytrunks. The method by which one pair of telephone lines of a subgroupare connected to the terminals of the finder switches will be describedin the course of this description.

The switches previously referred to may be ofthe type similar to thatdisclosed in the patent of Clement #1,107,153, patented August 11, 1914,while the switching relays referred to may be of any well known typeprovided with a plurality of sets of contact springs.

WVith this brief outline of the grouping arrangement of lines andswitches and with this brief reference to the equipment used it isbelieved that the invention will best be understood by describing themethod of extending a telephone connection from a call-' ing substationsuch as A to a numerical switch such as shown at the extreme right ofFig. 2, through which the calling line may be extended to a wantedtelephone line.

WVhen the subscriber at A removes his receiver from its switch hook, acircuit is completed for the line relay 5, extending from groundedbattery, winding of this relay,contact 6 and armature of relay 7,contact 8 and armature of relay 9, upper back contact and armature ofrelay 10, over the upper side of the calling line and through thesubstation circuits in series, inner armature and back contact of relay10, armature and contact 11 of relay 9, armature and contact 12 of relay7 to ground. Under the control of this circuit, the line relay isenergized and closes an operating circuit for the motor magnet 13 of theline switch extending from grounded battery, winding, back contact andarmature of this magnet, right hand armature and front contact of relay5, back contact 14 and armature of relay 7, test brush 15 to ground overtest conductors such as 16 of busy primary trunks.

-As soon as the line relay 5 is operated it closes an energizing circuitfrom ground, its left hand armature and front contact, lower winding ofrelay 18 to grounded battery. With relay 18 operated, the lines fromsubstations C and D are extended to the finder switches of this groupand a circuit is closed from grounded battery, winding, back contact andarmature of motor magnet 13, winding of relay 7, armature and frontcontact 19 of relay 18, front contact and armature of relay 5 to ground.This circuit, however, is ineffective to operate relay 7 since it isshort-circuited by ground through test brush 15 and test conductor 16 ofbusy trunks. As soon as an idle primary trunk is located, a conditionindicated by the ab sence of potential on its test terminal, theoperating circuit of the motor magnet 13 is no longer completed, and theshort circuit is removed from the winding of relay 7 ermitting it to beoperated. With the relay 7 actuated the calling line is extended throughcontacts 8 and 11 of relay 9, contacts 24 and 25 of relay 7, line switchbrushes 20 and 21, conductors 26 and 27 of the selected primary trunk toground at the upper armature of relay 28 and to grounded battery througharmature and contact 29 of relay 28 and winding of relay 30.

The relay 30 is thus energized in this circuit and closes a holdingcircuit from ground at its right hand armature and front contact,conductors 31 and 16, line switch brush 15, contact 32 and armature ofrelay 7 to grounded battery through the winding of magnet 13. At thistime a locking circuit is completed for relay 18 through its lowerwinding, contact 19 and armature, conductor 38 and contact 32 inmultiple with the holding circuit of relay 7. The line extending fromsubstation B, which is arbitrarily known as an even line, issimultaneously extended with the calling line to the even secondary lineswitch, over conductors 42 and 43.

As soon as the relay 3(), of Fig. 2, is operated it closes an actuatingcircuit for the motor magnet 44 of the odd secondary line switchtraceable from grounded battery, winding, armature and back contact ofthis magnet, outer armature and front contact of relay 30, inner lowerback contact and armature of relay 28, test brush 45, test terminalssuch as 46 of busy secondary trunks to ground at the front contacts andarmatures of relays such as 47 associated with busy secondary trunks.During the time that the motor magnet 44 is advancing the brushes 45,48, and 49 over busy trunks, a circuit is closed for the relay 28 fromgrounded battery, winding, armature, and back contact of motor magnet44, winding of relay 28, inner front contact, and armature of relay 30to ground. This circuit ineffective at this time, since the relay 28 isshort-cirouited during the time that test brush is encountering busytest terminals. When an idle secondary trunk is located. a conditionindicated by the absence of potential on its test terminal, theoperating circuit of the motor magnet 44 is interrupted, causing the oddsecondary line switch to be stopped with its brushes in engagement withan idle secondary trunk, and the relay 28, which is no longer shortcircuited, attracts its armatures to extend the calling line conductors26 and 27, of the primary trunk through the upper front contacts andarmatures of relay 28, through the brushes 48 and 49 of the oddsecondary line switch and the windings of relay 50 in series to groundand grounded battery respectively. Relay 50 is thus energized andeffects the operation of the slow releasing relay 47 which in turnapplies ground through its armature and front contact tothe multipletenninals, such as 46 of the selected secondary trunk circuit. This iseffective to complete a 1 holding circuit for the relay 28 extendingfrom test terminal 46 through test brush 45, lower inner armature,-front contact and winding of relay 28, to grounded battery, through thewinding ofniotor mag;

' net 44. i

The apparatus is now in condition to receive directive impulses from thecalling subscribers dial sender. It is believed that it is unnecessaryto describe the operation of setting up the remainder of the connection,but it will be understood that in response to these impulses selectorand connector switches of the well known type are directively operatedto extend the selected secondary trunk to the terminals of thewantedsubscribers line. As indicating the character of connectorcircuits which will function with the circuits of Fig. 1 and 2,reference is made to the connector switch circuits of Patent gi-1,382,012, granted to Winfred T. Powell, June 21, 192 1.

M Reference has been made in the description to the fact that the lineextending from substation B has been simultaneously extended by theoperation of primary line switch of Fig. lytoan even secondary lineswitch such as that shown in the lower right hand corner of Fig. 2.This'even secondary line switch is ineffective until the subscriber at Binitiates a call, when ito-perates to select an idle secondary trunk. Ifthe subscriber at B- initiates a call attliis time, the

relay 51 (Fig. 2) .is'energizedin a circuit which are connected toground potential,

applied at the front contact and armature of the relay 47. Under thecontrol of this circuit the motor magnet 104 advances the brushes 56, 58and until an idle secondary trunk is located at which time the motormagnet 104. ceases its'operatio-n and the switching relay 5st isoperated as described in connection with the switching relay 28, toextend the conductors 42 and 43 of the selected primary trunk to theconductors of the selected secondary trunk through brushes 58 and 59 ofthe even secondary line switch.

Let it now be assumed that when either or both of the lines extendingfrom substations A and B are in use in the manner indicated that eitheror both ofthe lines terminating at substations C and D initiate a call.First consider the method of extending a telephone connection fromstation C under these conditions. It will be remembered that theoperation of the relay 18 in tlie'manner already described has closedcontacts as and 35 so that when the subscriber at C initiates a. call, acircuit is closed trom grounded battery, winding of relay 60,,(appearing at the upper-left hand corner oi Fig. 2), armature andcontacts 61 ofrelay 62 condiizctor 63, contact 34 and armature of relayl8, conductor 64-, back contact and upper armature of relay 65. over theupper side of the line leading to sub-station C and through thesubstation circuits at C in series, over the lower side of the callingline, inner armature and back contact of relay 65, conductor 66,armature and contact '85 of relay 18, conductor 67, contact 68 andarmature of relay 62 to ground. The relay 60 is thus energized, andcloses an operating circuit for the relay 1. relay, lower back contactand armature of relay. 70, conductor 89, right hand armature andcontact-o1 relay 60 to ground. Re lay 17 when thus energized closes anoperating circuit for the motor magnet 69 of the line finder switch,extending from grounded battery, winding, back contact and armature ofmagnet '69, .inner armature and front contact of relay 17, cont-act 71and armature of. relay 72, test brush 7 3. test terminals such as 74, ornon-calling lines, continuity spring and back contact of relays similarto 62, armatures and back contacts of relays such as 60 ofnon-calling'lines to ground. Under the control of this circuit; themotor magnet 69 advances the brushes, 73, 75, 76, '77 and 78 of the linefinder switch until testbrush 73' encounters the test terminal of thecalling line which is indicated by the absence of ground potential ontest teuninal such as 74:, due to the fact that relay 60 associated withthe calling line has opened the circuit normally closed to groundthrough its left hand armature and back contact. During the time thatthe motor magnet 69 is operating, a circuit 18 also closed from groundedbattery, winding, back contact and armature of tins magnet, winding ofrelay 72 to ground at the left hand front contact and armature of relay17, but this circuitis ineffective at this time since it is shortcircnited by the ground applied through the inner front contact andarmature of relay 17 hen, however, the test brush 73 locates the callingline this short circuit is opened and the relay is operated over thecircuit ust described.

The conductors 63 and 67, are extended through brushes 77 and 780i theline finder and contacts79 and 80 of relay 72 through conductors similarto 81 and 82 of an idle primary trunk and thence to ground at the upperarmature and back contact of a relay similar to 28 and to groundedbattery. through the winding of a relay similar to 30 at an idle oddsecondary line switch. The relay corresponding to 30 is operated toapply a. holding ground over the conductor similar to 31 and conductorssimilar to 83 and 84, contact 85 and armature of relay 72 through abrush similar to 73, terminal 74, conductor 86, continuity spring andarmature of relay 62, winding of this relay to grounded battery. Thesecondary line switch last selected also operates in the manner alreadydescribed to select an idle numerical switch which will be directivelyoperated from the dial sender at substation C. It will be noted thatwhile the calling line C is being extended to an idle primary trunk hatthe telephone line at substation D is likewise extended throughconductors 87 and S8 and brushes similar to 76 and of the mentioned linefinder to an idle pri mary trunk leading to an idle even second ary lineswitch.

It will, of course, be understood that allotting means are provided toassign an idle finder switch for use. Any allotting means may beemployed, but in the present disclosure it is deemed advisable to showan extended starter wire arrangement. According to this arrangement assoon as the first line finder switch of the series is taken for use, itsrelay such as 7 O, is operated so that this starter wire 89 isextendedthrough the conductor 90, thus assigning for use, the nextfinder switch of the series. When the line switch of Fig. 1 seizes thetrunks leading to the secondary line switches of Fig. 2, the relay 70 isoperated from grounded battery, its winding, right hand back con tactand armature of relay 17, conductors 83 and 31 to ground at the frontcontact and armature of relay 30 or 51. In this manner the start wire iseiitended to allot an idle line finder for use.

In the foregoing description it has been seen that when one or both of apair of telephone lines is calling only the line switch individual tosaid group of four lines is operated, but it while the line switch is inuse one or both of the other pair of lines of the sub-group initiates acall, then a line finder switch comes into use. In practice the linesmay be grouped in such a way according to the period of the day in whichthey are customarily used that the line finder switches will rarely becalled into use.

It should be stated that when a line such as that extending fromsubstation A is call ing the slow releasing relay, such as 91, is inseries with one side of the line during the connection and it is bridgedby a non-inductive resistance. This relay is made slow releasing so thatground potential is main- When the line terminating at substation A iscalled, a connector seizes this line, a circuit is closed from ground,over conductor 92, armature and back contact of relay 91, winding ofrelay 10 to grounded battery. The relay 10 attracts its armatures andthereby disconnects this line from the brushes of its line switch toprevent false operation thereof.

At the time of the release of the telephone connection relay 4 7represented at the extreme right of Fig. 2 releases to remove theholding ground from test terminals 46 and 5'2, this permits relay 28 torelease and since this secondary line switch is of the'so-calledStay-put type it remains in the position last used in readiness forextending another call. II at this time the even secondary line switchis not in use, holding ground is re moved at the lowermost armature ofrelay 28 from holding conductors 81 and 16 which permits the release ofrelays 7 and 18 of Fig. 1 and since the primary line switch is of theStay-put type; that is, remains in the position last used, it is inreadiness for ex tending other calls.

In the event that both the odd and even secondary line switches of Fig.2 were in use simultaneously, then holding ground is maintained at theholding conductor 16 of the primary line switch until both of these lineswitches have been released, in one case the holding ground beingmaintained at the lowermost armature of the relay 28 and in the othercase at the uppermost armature and front contact of relay 54. In theevent that the call has been extended through the line finder switch,then when the odd and even secondary line switches have been released inthe manner indicated, holding ground is removed from holding conductor81 and multiple holding conductor 83 so that relays 72 and 62 of theline finder are released, and since the line finder switch is of thetype that remains in the position last used this switch is in readinessfor extending other telephone calls.

What is claimed is 1 In a telephone system, a plurality of telephonelines divided into groups, each group containing at least two pairs oftelephone lines, a line switch having brushes and fixed contacts, trunksterminating in said fixed contacts, the telephone lines of a group beingnormally related to the brushes of a line switch, means responsive tothe initiation of a call on one of a pair of telephone lines foroperating said line switch to extend said pair of telephone lines to apair of idle trunks, and means responsive to such connection forextending the other pair of lines of said group in selective rela: tionto other idle trunks.

'2. In a telephone system, telephtme lines arranged in groups, anindividual line switch for each group having movable brushes andfixedcontacts, the telephone lines of a group being normally inselective relation to its individual line switch, line finder switcheshaving fixed terminals and brushes, trunk circuits each terminating inthe brushes of a line finder switch and in the fixed contacts of aplurality of line switches, means responsive to the initiation of a callon one of the telephone lines for causing the line switch individual tosaid group of lines to con-nectcertain of the same to idle trunks, andmeansresponsive to such connection for extendi'ngwthe remainingtelephone lines'of said group to the fixed terminals of line finderswitches.

3. Ina telephone system, telephone lines arranged in groups, lineswitches having movable brushes and fixed contacts, the telephone linesof a group being, normally in selective relation to the brushes of aline switch, finder switches having fixed terminals and brushes, trmkcircuits each terminating in the brushes of a line finder switch andin the fixed terminals ofa plurality of line switches, means responsiveto the initiation of a call on one of the telephone lines for causingthe line switch of said group of lines to connect certain of the same toidle trunks, means responsive to such connection for extending theremaining,telephone lines of said group to the fixed terminals of agroup of line finder switches, and means for allotting idle finders foruse.

4. In a telephone system, groups of telephone lines, each group havingat least two pairs of telephone lines, line switches having movablebrushes and fixed contacts, one of said line switches being individualto each group of telephone lines, trunks multiply connected to fixedcontacts of said line switches, line finder switches having fixedterminals and movable brushes, a pair of said trunks terminating in themovable brushes of each of said line finder switches, a pair of relays,for each group of telephone lines having contacts through which thelines of its associated group are normally extended to brushes of itsindividual line switch and having other contacts by which said telephonelines on the energization of saidrelays may be con nected to theterminals of a plurality of said line finder switches, and meansresponsive to the initiation of a call on one of said telephone linesfor extending a pair of lines to idle trunks by way of the individualline switch and for operating one of said pair of relays to extend theother pair of said telephone lines to terminals of said lin finderswitches.

5. In a telephone system, a plurality of telephone lines arranged ingroups, each group having at least a pair of telephone lines, aplurality of trunks, a line switch individual to each group of telephonelines connectible to said trunks, line finders com mon to a plurality ofgroups of lines, trunk circuits, and means controlled by the extensionof a calling telephone line by way of one of said trunks and theindividual line switch of a group for extending certain of the othertelephone lines of the group to a line finder switch.

6. In a telephone system, a plurality of telephone lines arranged ingroups, each group having at least a pair of telephone lines a pluralityof trunks, a line switch in dividual to each group of telephone lines,line finder switches common to a plurality of grou-psof lines, trunkcircuits, and means controlled by the condition of the other lines ofthe group in which a telephone line is located, for determinatingwhether said individual line switch or one of said line finderswitchesis to extend said telephone line when it initiates a call.

7. In a telephone system, a plurality of telephone lines arranged ingroups, each group having at least two pairs of telephone lines, lineswitches having movable brushes and fixed terminals, one of said lineswitches being individual to a group of telephone lines, the telephonelines of a group being normally extended to its line switch, trunks.means for causing said line switch to extend a pair of lines to a pairof trunks simultaneously, aplurality of line finder switches, eachhaving fixed contacts and movable brushes, :1 pair of said trunksterminating in the movable brushes of a line finder switch, meansfunctioning under certain con ditions to cause an idle line finderswitch to extend its pair of trunks to a pair of telephone lines, all ofthe telephone lines of a group normally having as a first choice theirindividual line switch if all of the telephone lines of this group areidle, but having one of said line finder switches as a second choice ifone of said other telephone lines of this group is in use when itoriginates a call. I

8. In a telephone system, a plurality of telephone lines divided intogroups, each group containing at least two pairs of tele phone lines, aline switch having brushes and fixed contacts, trunks terminating insaid fixed contacts, the telephone lines of a group being normally inselective relation to a line switch, means responsive to the initiationof a call on one of a pair of telephone lines for operating said lineswitch to extend a pair of telephone lines to a pair of idle trunks, andmeans responsive to such connection for extending the other pair oflines of said group into selective relation to other idle trunks.

9. In a telephone system, a plurality of telephone lines divided intogroups, each group containin at least two pairs of telephone lines, aine switch having brushes and fixed contacts, trunks terminating in saidfixed contacts, the telephone lines of a group being normally inselective relation with the movable brushes of a line switch, meansresponsive to the initiation of ai call on one of a pain'of telephonelines for operating said line switch to extend said pair oi telephonelines to a pair of idle trunks, and common non-numerical switching meansresponsive to such connection for extending the other pair of lines ofsaid roup in operative relation to other idle trunxs.

10. In a telephone system, a plurality of telephone lines arranged ingroups, a line switch individual to each group of telephone lines, aplurality of trunks terminating in said line switches, line finderswitches in which said trunks and telephone lines terminate, the lineswitch of a group being arranged to extend certain of said telephonelines to idle trunks on the initiation of a call on onerot' the lines ofa group, and means to assign an idle line finder switch to extend theremaining telephone lines of said group to other idle trunks on theinitiation of calls thereon.

11. In a telephone system, a plurality of lineswitches and in themovable elements tacts of one of said relays, means responsive to theinitiation of a call on one of the telephone lines of a pair foroperating its individual'line switch to extend said pair of telephonelines to a pair of idle trunks,

means responsive to said extension for operating one of the relays ofsaid group for extending the other pair of telephone lines of saidigroupto the contacts of said group of finder switches, and means responsiveto the initiation of a call on one of the lines or" said last mentionedpair for extending said pair of telephone lines to a pair of idle trunkcircuits through a line finder switch.

12'. In a telephone system, groups of telephone lines, each group havingtwo pairs of telephone lines, two pairs of trunks for the use of thetelephone lines of each group, a line switch individual to a group oftelephone lines, relays for normally extending both pairs of telephonelines to a pair of idle trunks terminating in said individual lineswitch, trunk finder switches in which the other pair of trunksterminate, and means efifective on the initiation of a call on one pairof telephone lines for disconnecting the other pair of telephone linesof the group from the trunks extending to said line switchand folconnecting the same to the pair of trunks leading to the line finderswitches. is

In witness whereof, I hereunto subscribe my name this 15th day ofSeptember, A. D.

WINFRED T. POWELL.

